@olydoug
I know what you are saying, and if used in deep snow and driven slowly, the snow will help keep the rear wheels tracking straight. But, I can tell you from experience with all kinds of vehicles, the more traction on front on hard slippery surfaces is real scary if you brake hard.
This reference sums up the attributes and disadvantages of putting chains on different vehicles and their over all effect. The rear traction bias is essential for lateral stability. Imho, you have literally multiplied the reasoning behind the adage of best tires on rear by ten fold when using chains only on the fronts.
http://www.rubicon-trail.com/jeep101/chains.html